1. Field of the Invention
The present invention relates to an indoor localization method, more particularly to a method of reducing power consumption of a radio badge in a boundary detection localization system.
2. Description of the Related Art
Sensor network technologies have undergone significant advances in recent times. This has enabled a variety of applications in consumer electronics. For example, sensor networks are increasingly being used for asset tracking in warehouses, patient monitoring in medical facilities, using location to infer activities of daily living (ADL) at home, and other such object-tracking applications.
One class of localization technology aims at detecting the crossing of boundaries. For example, boundary detection localization may be used for detection of troop movement, such as by detecting whether enemy troops have crossed a national borderline, for theft control, such as by detecting the exiting of products from a store, or for child safety, such as by detecting whether a young child has entered a balcony area.
Early detection is essential for boundary detection services. That is, users of such technology desire to be notified of boundary crossing events before a tracked target goes too far into a critical region. One way to ensure early detection is frequent sampling via a high sampling rate that is fixed, where the sampling rate is defined as the rate at which an infrastructure component of the localization system and mobile units thereof are triggered to perform communication and computation. However, the energy consumption of the mobile units, which are attached to or carried by tracked targets and are typically small battery-powered tags or radio badges, is directly proportional to the sampling rate.
The problem with fixed-rate sampling is that while the sampling rate can be set high to provide real-time location information, when the target is far from the critical region where the requirement for timely service is not as high, a high sampling rate and the high power requirements associated therewith will be unnecessary. This is particularly problematic for the mobile units.